In the application of electrical systems, there always existing a plurality of electrical circuits coupled to different reference grounds which are isolated from each other. respectively. A traditional method is using different power sources to supply power for each of these electrical circuits, wherein different power sources are coupled to different reference grounds which are isolated from each other. As shown in FIG. 1, an electrical system 001 comprises a first receiving circuit 10 and a second receiving circuit 20. Wherein the first receiving circuit 10 is coupled to a first reference ground GND1, the second receiving circuit 20 is coupled to a second reference ground GND2. A power source P1 is configured to supply a power signal Vdc1 for the first receiving circuit 10, and a power source P2 is configured to supply a power signal Vdc2 for the second receiving circuit 20. Wherein the power source P1 is coupled to the first reference ground GND1, the power source P2 is coupled to the second reference ground GND2. However, this traditional method of using two separate power sources will increase the cost and volume of the electrical system.